add API to change default config on image decoders.

May be called by the browser to get high-quality images when running in a 32bit window

graphics/java/android/graphics/BitmapFactory.java

@@ -558,6 +558,30 @@ public class BitmapFactory {
         return decodeFileDescriptor(fd, null, null);
     }
 
+    /**
+     * Set the default config used for decoding bitmaps. This config is
+     * presented to the codec if the caller did not specify a preferred config
+     * in their call to decode...
+     *
+     * The default value is chosen by the system to best match the device's
+     * screen and memory constraints.
+     *
+     * @param config The preferred config for decoding bitmaps. If null, then
+     *               a suitable default is chosen by the system.
+     *
+     * @hide - only called by the browser at the moment, but should be stable
+     *   enough to expose if needed
+     */
+    public static void setDefaultConfig(Bitmap.Config config) {
+        if (config == null) {
+            // pick this for now, as historically it was our default.
+            // However, if we have a smarter algorithm, we can change this.
+            config = Bitmap.Config.RGB_565;
+        }
+        nativeSetDefaultConfig(config.nativeInt);
+    }
+
+    private static native void nativeSetDefaultConfig(int nativeConfig);
     private static native Bitmap nativeDecodeStream(InputStream is, byte[] storage,
             Rect padding, Options opts);
     private static native Bitmap nativeDecodeFileDescriptor(FileDescriptor fd,